-----------------------------------------------------------------------------
-- |
-- Module      :  Network.XmlRpc.THDeriveXmlRpcType
-- Copyright   :  (c) Bjorn Bringert 2003-2005
-- License     :  BSD-style
--
-- Maintainer  :  bjorn@bringert.net
-- Stability   :  experimental
-- Portability :  non-portable (requires extensions and non-portable libraries)
--
-- Uses Template Haskell to automagically derive instances of 'XmlRpcType'
--
------------------------------------------------------------------------------

{-# LANGUAGE CPP             #-}
{-# LANGUAGE TemplateHaskell #-}

module Network.XmlRpc.THDeriveXmlRpcType (asXmlRpcStruct) where

import           Control.Monad            (liftM, replicateM)
import           Data.List                (genericLength)
import           Data.Maybe               (maybeToList)
import           Language.Haskell.TH
import           Network.XmlRpc.Internals hiding (Type)

-- | Creates an 'XmlRpcType' instance which handles a Haskell record
--   as an XmlRpc struct. Example:
-- @
-- data Person = Person { name :: String, age :: Int }
-- $(asXmlRpcStruct \'\'Person)
-- @
asXmlRpcStruct :: Name -> Q [Dec]
asXmlRpcStruct :: Name -> Q [Dec]
asXmlRpcStruct name :: Name
name =
    do
    Info
info <- Name -> Q Info
reify Name
name
    Dec
dec <- case Info
info of
                     TyConI d :: Dec
d -> Dec -> Q Dec
forall (m :: * -> *) a. Monad m => a -> m a
return Dec
d
                     _ -> String -> Q Dec
forall (m :: * -> *) a. MonadFail m => String -> m a
fail (String -> Q Dec) -> String -> Q Dec
forall a b. (a -> b) -> a -> b
$ Name -> String
forall a. Show a => a -> String
show Name
name String -> String -> String
forall a. [a] -> [a] -> [a]
++ " is not a type constructor"
    Dec -> Q [Dec]
mkInstance Dec
dec

mkInstance :: Dec -> Q [Dec]
#if MIN_VERSION_template_haskell(2,11,0)
mkInstance :: Dec -> Q [Dec]
mkInstance  (DataD _ n :: Name
n _ _ [RecC c :: Name
c fs :: [VarBangType]
fs] _) =
#else
mkInstance  (DataD _ n _ [RecC c fs] _) =
#endif
    do
    let ns :: [(Name, Bool)]
ns = ((VarBangType -> (Name, Bool)) -> [VarBangType] -> [(Name, Bool)]
forall a b. (a -> b) -> [a] -> [b]
map (\ (f :: Name
f,_,t :: Type
t) -> (Name -> Name
unqual Name
f, Type -> Bool
isMaybe Type
t)) [VarBangType]
fs)
    [Dec]
tv <- [(Name, Bool)] -> Q [Dec]
mkToValue [(Name, Bool)]
ns
    [Dec]
fv <- Name -> [(Name, Bool)] -> Q [Dec]
mkFromValue Name
c [(Name, Bool)]
ns
    [Dec]
gt <- Q [Dec]
mkGetType
    (Dec -> [Dec]) -> Q Dec -> Q [Dec]
forall (m :: * -> *) a1 r. Monad m => (a1 -> r) -> m a1 -> m r
liftM (Dec -> [Dec] -> [Dec]
forall a. a -> [a] -> [a]
:[]) (Q Dec -> Q [Dec]) -> Q Dec -> Q [Dec]
forall a b. (a -> b) -> a -> b
$ CxtQ -> TypeQ -> [Q Dec] -> Q Dec
instanceD ([TypeQ] -> CxtQ
cxt []) (TypeQ -> TypeQ -> TypeQ
appT (Name -> TypeQ
conT ''XmlRpcType)
                                    (Name -> TypeQ
conT Name
n))
              ((Dec -> Q Dec) -> [Dec] -> [Q Dec]
forall a b. (a -> b) -> [a] -> [b]
map Dec -> Q Dec
forall (m :: * -> *) a. Monad m => a -> m a
return ([Dec] -> [Q Dec]) -> [Dec] -> [Q Dec]
forall a b. (a -> b) -> a -> b
$ [[Dec]] -> [Dec]
forall (t :: * -> *) a. Foldable t => t [a] -> [a]
concat [[Dec]
tv, [Dec]
fv, [Dec]
gt])

mkInstance _ = String -> Q [Dec]
forall a. HasCallStack => String -> a
error "Can only derive XML-RPC type for simple record types"


isMaybe :: Type -> Bool
isMaybe :: Type -> Bool
isMaybe (AppT (ConT n :: Name
n) _) | Name
n Name -> Name -> Bool
forall a. Eq a => a -> a -> Bool
== ''Maybe = Bool
True
isMaybe _ = Bool
False


unqual :: Name -> Name
unqual :: Name -> Name
unqual = String -> Name
mkName (String -> Name) -> (Name -> String) -> Name -> Name
forall b c a. (b -> c) -> (a -> b) -> a -> c
. String -> String
forall a. [a] -> [a]
reverse (String -> String) -> (Name -> String) -> Name -> String
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (Char -> Bool) -> String -> String
forall a. (a -> Bool) -> [a] -> [a]
takeWhile (Char -> String -> Bool
forall (t :: * -> *) a. (Foldable t, Eq a) => a -> t a -> Bool
`notElem` [':','.']) (String -> String) -> (Name -> String) -> Name -> String
forall b c a. (b -> c) -> (a -> b) -> a -> c
. String -> String
forall a. [a] -> [a]
reverse (String -> String) -> (Name -> String) -> Name -> String
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Name -> String
forall a. Show a => a -> String
show

mkToValue :: [(Name,Bool)] -> Q [Dec]
mkToValue :: [(Name, Bool)] -> Q [Dec]
mkToValue fs :: [(Name, Bool)]
fs =
    do
    Name
p <- String -> Q Name
newName "p"
    Name -> [PatQ] -> ExpQ -> Q [Dec]
simpleFun 'toValue [Name -> PatQ
varP Name
p]
                (ExpQ -> ExpQ -> ExpQ
appE (Name -> ExpQ
varE 'toValue)
                          (ExpQ -> ExpQ -> ExpQ
appE [| concat |] (ExpQ -> ExpQ) -> ExpQ -> ExpQ
forall a b. (a -> b) -> a -> b
$ [ExpQ] -> ExpQ
listE ([ExpQ] -> ExpQ) -> [ExpQ] -> ExpQ
forall a b. (a -> b) -> a -> b
$ ((Name, Bool) -> ExpQ) -> [(Name, Bool)] -> [ExpQ]
forall a b. (a -> b) -> [a] -> [b]
map (Name -> (Name, Bool) -> ExpQ
fieldToTuple Name
p) [(Name, Bool)]
fs))


simpleFun :: Name -> [PatQ] -> ExpQ -> Q [Dec]
simpleFun :: Name -> [PatQ] -> ExpQ -> Q [Dec]
simpleFun n :: Name
n ps :: [PatQ]
ps b :: ExpQ
b = [Q Dec] -> Q [Dec]
forall (t :: * -> *) (m :: * -> *) a.
(Traversable t, Monad m) =>
t (m a) -> m (t a)
sequence [Name -> [ClauseQ] -> Q Dec
funD Name
n [[PatQ] -> BodyQ -> [Q Dec] -> ClauseQ
clause [PatQ]
ps (ExpQ -> BodyQ
normalB ExpQ
b) []]]

fieldToTuple :: Name -> (Name,Bool) -> ExpQ
fieldToTuple :: Name -> (Name, Bool) -> ExpQ
fieldToTuple p :: Name
p (n :: Name
n,False) = [ExpQ] -> ExpQ
listE [[ExpQ] -> ExpQ
tupE [String -> ExpQ
stringE (Name -> String
forall a. Show a => a -> String
show Name
n),
                                         ExpQ -> ExpQ -> ExpQ
appE (Name -> ExpQ
varE 'toValue)
                                         (ExpQ -> ExpQ -> ExpQ
appE (Name -> ExpQ
varE Name
n) (Name -> ExpQ
varE Name
p))
                                        ]
                                 ]
fieldToTuple p :: Name
p (n :: Name
n,True) =
    [| map (\v -> ($(stringE (show n)), toValue v)) $ maybeToList $(appE (varE n) (varE p)) |]

mkFromValue :: Name -> [(Name,Bool)] -> Q [Dec]
mkFromValue :: Name -> [(Name, Bool)] -> Q [Dec]
mkFromValue c :: Name
c fs :: [(Name, Bool)]
fs =
    do
    [Name]
names <- Int -> Q Name -> Q [Name]
forall (m :: * -> *) a. Applicative m => Int -> m a -> m [a]
replicateM ([(Name, Bool)] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [(Name, Bool)]
fs) (String -> Q Name
newName "x")
    Name
v <- String -> Q Name
newName "v"
    Name
t <- String -> Q Name
newName "t"
    Name -> [PatQ] -> ExpQ -> Q [Dec]
simpleFun 'fromValue [Name -> PatQ
varP Name
v] (ExpQ -> Q [Dec]) -> ExpQ -> Q [Dec]
forall a b. (a -> b) -> a -> b
$
               [StmtQ] -> ExpQ
doE ([StmtQ] -> ExpQ) -> [StmtQ] -> ExpQ
forall a b. (a -> b) -> a -> b
$ [PatQ -> ExpQ -> StmtQ
bindS (Name -> PatQ
varP Name
t) (ExpQ -> ExpQ -> ExpQ
appE (Name -> ExpQ
varE 'fromValue) (Name -> ExpQ
varE Name
v))] [StmtQ] -> [StmtQ] -> [StmtQ]
forall a. [a] -> [a] -> [a]
++
                      (PatQ -> (Name, Bool) -> StmtQ)
-> [PatQ] -> [(Name, Bool)] -> [StmtQ]
forall a b c. (a -> b -> c) -> [a] -> [b] -> [c]
zipWith (Name -> PatQ -> (Name, Bool) -> StmtQ
forall a. Show a => Name -> PatQ -> (a, Bool) -> StmtQ
mkGetField Name
t) ((Name -> PatQ) -> [Name] -> [PatQ]
forall a b. (a -> b) -> [a] -> [b]
map Name -> PatQ
varP [Name]
names) [(Name, Bool)]
fs [StmtQ] -> [StmtQ] -> [StmtQ]
forall a. [a] -> [a] -> [a]
++
                      [ExpQ -> StmtQ
noBindS (ExpQ -> StmtQ) -> ExpQ -> StmtQ
forall a b. (a -> b) -> a -> b
$ ExpQ -> ExpQ -> ExpQ
appE [| return |] (ExpQ -> ExpQ) -> ExpQ -> ExpQ
forall a b. (a -> b) -> a -> b
$ [ExpQ] -> ExpQ
appsE (Name -> ExpQ
conE Name
cExpQ -> [ExpQ] -> [ExpQ]
forall a. a -> [a] -> [a]
:(Name -> ExpQ) -> [Name] -> [ExpQ]
forall a b. (a -> b) -> [a] -> [b]
map Name -> ExpQ
varE [Name]
names)]

mkGetField :: Name -> PatQ -> (a, Bool) -> StmtQ
mkGetField t :: Name
t p :: PatQ
p (f :: a
f,False) = PatQ -> ExpQ -> StmtQ
bindS PatQ
p ([ExpQ] -> ExpQ
appsE [Name -> ExpQ
varE 'getField,
                                           String -> ExpQ
stringE (a -> String
forall a. Show a => a -> String
show a
f), Name -> ExpQ
varE Name
t])
mkGetField t :: Name
t p :: PatQ
p (f :: a
f,True) = PatQ -> ExpQ -> StmtQ
bindS PatQ
p ([ExpQ] -> ExpQ
appsE [Name -> ExpQ
varE 'getFieldMaybe,
                                          String -> ExpQ
stringE (a -> String
forall a. Show a => a -> String
show a
f), Name -> ExpQ
varE Name
t])

mkGetType :: Q [Dec]
mkGetType :: Q [Dec]
mkGetType = Name -> [PatQ] -> ExpQ -> Q [Dec]
simpleFun 'getType [PatQ
wildP]
             (Name -> ExpQ
conE 'TStruct)